For the last several months, a bizarre, miniaturized replay of the British mad cow crisis has gripped the United States. Except this time, there's been no cattle epidemic and no human victims. Just speculation, publicity, more speculation, more publicity.
In part, the furor was triggered by our own regulators. In early January, the Food and Drug Administration began clamping down on feed mills to ensure that safety measures intended to prevent mad cow-type diseases from circulating in this country are strictly followed. This was business as usual. It is the agency's job to consider worst-case scenarios, then to work with industry to reduce risks.
Within days of the FDA's action, however, the media speculation began. There were reports that mad cow disease might occur spontaneously and that the U.S. might have mad cow disease in its livestock feed. There were not only reports of mad cows in the U.S., but mad elk, mad deer and mad hunters. There were even rumors of mad squirrels.
As television reporters joined the fray, and pollsters were dispatched to measure our anxiety, the notional danger swung from what we eat here to what U.S. travelers might have encountered while dining in Europe. An argument erupted over the safety of blood. By late last week, the American Red Cross was disclosing plans to unilaterally disqualify thousands of Americans who had lived more than a year in Western Europe from giving blood.
Blood bank switchboards lit up with calls from donors worried about a steak and kidney pie they had eaten in England or questioning whether the semester they had spent at the Sorbonne made them ineligible to give blood.
Federal officials struggled to allay fears. The FDA has taken "very aggressive steps" to protect blood and other products, stressed Dr. Jay Epstein, director of the FDA's office of blood research and review. "These steps are directed at a theoretical risk."
How theoretical? The problem isn't that the risk of contracting mad cow disease on holiday in Europe is remote; it's that it's almost too remote to calculate. Its deadly human form is a tragedy, but outrage at this too often obscures that it is also very rare. Last year in Britain it struck one out of every two million people. To understand how mad cow disease spreads, and how to prevent it, one has to look at its larger school of disorders. This is called transmissible spongiform encephalopathies. Big name, simple meaning: transmissible, i.e., they're catching; spongiform: They leave sponge-like holes; encephalopathy: The holes appear in the brain.
Spongy-brain disease dates back to 1732, when a disease in sheep was named scrapie because the infected animals would scrape themselves. The disease, endemic in European sheep for centuries, was brought to the United States in 1947 from sheep imported from Britain. Since 1952, the U.S. Department of Agriculture has tried to contain the disease by routinely destroying affected animals. The latest destruction order, of three flocks of sheep in Vermont, generated international headlines. The sheep had been imported from Europe, and worries swirled that they had brought mad cow disease. It now appears that four sheep among many hundreds had scrapie
Sheep scrapie has never been shown to infect people, in spite of extensive epidemiological studies that looked for an association. The first hint that scrapie was part of a larger school of diseases, including some deadly to humans, came in the 1950s, when researcher Dr. Daniel Carleton Gajdusek discovered a disease endemic among the Fore-speaking tribe of Papua, New Guinea. The disease was called kuru. It means "tremble" and referred to the uncontrollable shaking of the victims.
Gajdusek, who knew of the Fore's habit of cannibalizing their dead, helped to discourage the practice, and kuru died out. Back in the United States, tipped by a veterinarian that kuru resembled a sheep disease, he performed research that found that not only was kuru a relative of scrapie, but so was a disease discovered in 1920s Germany, called Creutzfeldt-Jakob disease. In 1976, Gajdusek received a Nobel Prize for discovering the new school of diseases.
Even so, spongy-brain diseases were still quite rare in people, and only a handful of scientists worldwide were familiar with them. By the late 1970s, it was becoming clear that Creutzfeldt-Jakob disease kills about one in a million every year, and that this rate held the world over.
In Scotland, British scientists perfected a technique to strain-type these new diseases. Their work has allowed scientists to tell one type of spongy-brain disease from another. They helped record new versions as these were spotted on mink farms in Wisconsin in 1947 and elk in the Western U.S. in the late 1970s. In 1985, a fearful new strain erupted in England: bovine spongiform encephalopathy, otherwise known as "mad cow disease."